Field of the Invention
The present invention relates to a hybrid vehicle, and particularly to a hybrid vehicle including an internal combustion engine, a power storage device, and an electric motor that receives electric power from the power storage device to generate travel driving force.
Description of the Background Art
Japanese Patent Laying-Open No. 2013-252853 discloses a hybrid vehicle implementing a CD (Charge Depleting) mode and a CS (Charge Sustaining) mode. In the CD mode, EV (Electric Vehicle) traveling is mainly executed while allowing HV (Hybrid Vehicle) traveling, so that an SOC (State Of Charge) of a power storage device is actively consumed. In the CS mode, the SOC is controlled so as to fall within a prescribed range by switching the traveling mode between HV traveling and EV traveling as appropriate. In EV traveling, the vehicle travels using only a motor generator while stopping its engine. In HV traveling, the vehicle travels while operating its engine (see Japanese Patent Laying-Open No. 2013-252853).
Due to recent progress in the power electronics technique, motors, inverters, power storage devices and the like have been improved in performance. Also due to such a technical background, hybrid vehicles have been increased in flexibility in selecting a driving force source (an engine or a motor). Thus, it is desirable for a hybrid vehicle implementing a CD mode and a CS mode to achieve a special traveling performance with a high level of user satisfaction particularly in the CD mode.
In general, the relation between (i) the responsiveness of the vehicle driving torque to the operation of an accelerator pedal and (ii) shock, sound or the like resulting from torque changes (which will be hereinafter comprehensively referred to as “shock”) is a trade-off relation. Thus, the responsiveness of the vehicle driving torque is set in accordance with the characteristics required for a vehicle. However, if the responsiveness of the vehicle driving torque is equally set, a special traveling performance with a high level of user satisfaction cannot be achieved in the CD mode.